In recent years, there is an imaging element in which a backside illumination type imaging chip and a signal processing chip are laminated. In such an imaging element, it has been suggested that pixels arranged in an array formed on a backside illumination type imaging chip are divided into unit pixel regions constituted by a plurality of pixels, and a pixel signal of each pixel is read out in a predetermined order for each unit pixel region (e.g., see Patent Document 1).
In the invention of Patent Document 1, the readout of the pixel signal is controlled such that positions of pixels having the same readout order of the pixel signals within adjacent unit pixel regions become line-symmetric with respect to the boundary of the unit pixel regions, thereby suppressing image distortion at the boundary of the unit pixel regions.